RGB matrix-color based on the wavelength

wavelength2rgb.jl

"""
Returns an RGB matrix-color based on the wavelength input in nm.
RBG = wavelength2rgb(λ)
Wavelength range: 380nm and 780nm, black otherwise.
Source: https://stackoverflow.com/questions/3407942/rgb-values-of-visible-spectrum
"""
function wavelength2rgb(λ::AbstractArray{<:Number})
    Γ = 0.8
    # warm up
    R = Array{Float64, 1}(undef, length(λ))
    G = similar(R)
    B = similar(R)
    intensityCorrection = similar(R)
    R[380 .<= λ .<= 440] = -(λ[380 .<= λ .<= 440] - 440.) ./ (440. - 380.)
    G[380 .<= λ .<= 440] = 0. * λ[380 .<= λ .<= 440]
    B[380 .<= λ .<= 440] = 1. + (0. * λ[380 .<= λ .<= 440])
    R[440 .< λ .<= 490] = 0.
    G[440 .< λ .<= 490] = ((λ[440 .< λ .<= 490] - 440.) ./ (490. - 440.))
    B[440 .< λ .<= 490] = 1.
    R[490 .< λ .<= 510] = 0.
    G[490 .< λ .<= 510] = 1.
    B[490 .< λ .<= 510] = (-(λ[490 .< λ .<= 510] - 510.) ./ (510. - 490.))
    R[510 .< λ .<= 580] = ((λ[510 .< λ .<= 580] - 510.) ./ (580. - 510.))
    G[510 .< λ .<= 580] = 1.
    B[510 .< λ .<= 580] = 0.
    R[580 .< λ .<= 645] = 1.
    G[580 .< λ .<= 645] = (-(λ[580 .< λ .<= 645] - 645.) ./ (645. - 580.))
    B[580 .< λ .<= 645] = 0.
    R[645 .< λ .<= 780] = 1.
    G[645 .< λ .<= 780] = 0.
    B[645 .< λ .<= 780] = 0.
    R[λ .> 780] = 0.
    R[λ .< 380] = 0.
    G[λ .> 780] = 0.
    G[λ .< 380] = 0.
    B[λ .> 780] = 0.
    B[λ .< 380] = 0.
    # LET THE INTENSITY SSS FALL OFF NEAR THE VISION LIMITS
    intensityCorrection[λ .> 700] = 0.3 + 0.7 * (780. - λ[λ .> 700]) ./ (780. - 700.)
    intensityCorrection[λ .< 420] = 0.3 + 0.7 * (λ[λ .< 420] - 380.) ./ (420. - 380.)
    intensityCorrection[420 .< λ .< 700]= 1.
    # GAMMA ADJUST
    R = (intensityCorrection .* R).^Γ
    G = (intensityCorrection .* G).^Γ
    B = (intensityCorrection .* B).^Γ
    # # Multiply by 255
    # R = R * 255
    # G = G * 255
    # B = B * 255
    return [R G B]
end